Joseph Raymond Hilton disclosed an improvement in and relating to breathing apparatus in his U. K. Patent Application GB 2,032,284 A comprising a housing which may be a half face mask, a full face mask or a helmet, sealed to the wearer to define a substantially closed chamber surrounding the wearer's nose and mouth, in which air is supplied to the helmet by a fan and air exits form the chamber through an exhale valve for a forced circulation of the breathing air of the wearer, and which, however, has the following drawbacks:
1. The mask built in a helmet is very heavy and is not suitable for a worker who works in an environment having minor dusts or pollutants laden in the air and having no danger of falling objects harmful for the worker.
2. Even a wearer's face may be fully shielded in the mask and helmet for preventing dust pollution, the shielding mask, except the exhale valve, may not well dissipate the heat accumulated within the mask, thereby causing uncomfortable feeling to the mask wearer.
3. The complete set of helmet, mask, fan, motor and dry cells seems to be complex and may increase production cost and maintenance problems.
4. Whenever a power failure is caused, the forced circulation effect will stop which will greatly influence a wearer's breathing difficulty.
5. The wearer's mouth is shielded by a mask which makes conversing with other people difficult.
The present inventor has found the drawbacks of a conventional breathing apparatus and invented the present miniature respiratory apparatus.